Trying to install Skype using this ubuntuhandbook.org guide
I get this error on running reload cache (step 2 1st part):
W: GPG error: https://repo.skype.com/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1F3045A5DF7587C3
W: The repository 'https:repo.skype.com/deb stable InRelease' is not signed.
How can I fix it?